DNA traces blood lines; documentation who lives together. The Hemmings family, because of their blood relationship with the Jefferson family, had the option of selectively misplacing (or even altering) documentation so they could pass as white, an avenue many of them chose.
Now that it is no longer fashionable to be white, they can use their DNA testing to highlight their African roots. The Hemmings are just one famous example.
Pure speculation on my part, but 18th century Indians, especially in Pennsylvania (but I would assume among the Cherokee as well), were subjected to a severe reduction of their ranks, not only due to contacts with disease to which they had no immunity (especially smallpox) but internal resource conflicts with competing tribes as they were pushed west into every shrinking territory.
Incorporation of enemy captives, including white settlers, into their tribes was a part of the culture. After a generation or so, these captives would lose their former identity completely and become a member of the tribe. This was not a rare happening, it was quite normal. Indeed, some tribes on the frontier (from both the Indian and the white perspective) were majority captive.
Indeed, Ben Franklin observed that captives steeped in Indian culture, once they made the conversion, could not be cajoled back into white culture because the material benefits of doing so was zero to small whereas the loss of freedom was too great.
So your documentation may be true, but no DNA markers because former captives married former captives. Rare for sure, but not impossible.
Probably a lot of what you posted is/was true.
The math on our father’s side is fairly straight forward.
Apparently, if the DNA is on our mother’s side, the rules change and ancestors often don’t show.
Like Garth Tater, my logical mind can’t handle this DNA stuff when our female ancestors were involved.
Thanks good possibilities.